glacier melting

 

The Thwaites glacier in Antarctica is vulnerable to rising sea temperatures.

According to new research, Antarctic glaciers may be more sensitive to changes in sea temperature than previously thought.

Under the massive Thwaites glacier, the British Antarctic Survey and the US Antarctic Program installed underwater robots and sensors to study melting.

Thwaites, a glacier the size of Great Britain, is one of the world’s fastest-changing.

Scientists are particularly concerned about its vulnerability to climate change because, in the event that it completely melted, it would raise global sea levels by half a meter.

According to the new findings, a glacier’s eventual disappearance may be further advanced by even small amounts of melting.

One of the largest investigations ever carried out anywhere on the White Continent includes the joint survey at Thwaites.

The glacier’s “grounding line,” which is the point at which the ice flowing off the land and along the seabed rises to form a huge platform, has receded 14 kilometers since the late 1990s.

This grounding line is currently receding by more than a kilometer per year in some locations, and due to the seabed’s landward-sloping shape, this process is likely to accelerate.

British Antarctic Survey (BAS) researchers used boreholes in the ice to drop sensors into the water below for the new study.

They discovered less melting than anticipated at those higher temperatures, despite the fact that warmer water circulates beneath the shelf; A layer of clean water was acting as an insulator against additional losses.

Using computer modeling, they also discovered that the volume of melting was not the most important factor in a glacier’s retreat, which is troubling.

“It’s good that the melt rate is low but what matters is how the melt rate changes,” explained BAS oceanographer Dr Pete Davis. “To push an ice shelf out of equilibrium, we need to increase the melt rate. So even if the melt rate increases just a small amount, it can still drive rapid retreat.”

The flat and relatively uniform underside of the glacier was the location of the observations that revealed less melting than anticipated.

But the images that the underwater robot Icefin took as part of the same joint survey for the US Antarctic program showed that things were often much more complicated.

“What we could see is that instead of this kind of flat ice that we had all pictured, there were all kinds of staircases and cracks in the ice that weren’t really expected,” said Cornell University-based researcher Britney Schmidt, who guided Icefin under Thwaites using a video monitor and a games console controller.

Using a hot-water drill, the British Antarctic Survey (BAS) cut a 600-meter-long hole through the ice to get the torpedo-shaped Icefin under Thwaites. After that, the winched sub was brought down to begin its exploration.

The robot reached the grounding line of the glacier after Dr. Schmidt’s team performed five dives in succession.

The onboard sensors of Icefin indicated that the influx of warm water from the wider ocean is specifically eroding the Thwaites bottom in these specific locations.

“Basically, the warm water is getting into the weak spots and making them even weaker,” said Dr Schmidt. “What this allows us to do now is to put this kind of information into our predictive models to understand how the ice shelf is going to break down, and when.”

Dr. Davis went on to say that the lessons learned at Thwaites probably apply to all of the other glaciers in the area that are also retreating.

This week, the scientific journal Nature published two academic papers describing the work. Icefin is the focus of one, and borehole profilers are the focus of the other.

Prof. David Vaughan, the former director of science at BAS, is one of the contributing authors on the Icefin paper. The polar agency announced his death last week.

Prof. Vaughan had established himself as one of the world’s leading glaciologists for more than 35 years.

He supported the UK-US Thwaites project and served as its co-lead until his illness forced him to step down.

His final excursion south was his journey to see the research described in the two papers from Wednesday.

Prof Helen Fricker, from the Scripps Institution of Oceanography at the University of California, San Diego, is in Antarctica currently. She said: “David was a brilliant, thoughtful and engaging scientist who was a role model for so many. He was a leader in the field, making important geophysical insights about the Antarctic ice sheet and how it is changing.

“He led with dignity, grace, humour and compassion, and was actively supportive of young scientists, especially minorities. Antarctic science has lost a true hero and he will be deeply missed.”

 

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